Incomplete variants.json endpoint

Hello

I´m just starting using Shopify API and tried to get list of variants, not from product level but from variants itself :

https://.myshopify.com/admin/api/2022-07/variants.json?fields=id,title,product_id

I discovered that not all the products that have variants are listed , if I use the endpoint products//variants.json that returns the variants for the specific product, but If I try to get variants from variants endpoint products are missing, has anybody seen this problem before?

Thank you in advance.